In an LTE (Long Term Evolution) cellular mobile communication system, error correction by HARQ (Hybrid ARQ) has been applied. The error correction by the HARQ has been applied to not only data transmission of bidirectional communication between a base station and a mobile station but also data transmission of unidirectional communication for notification information or the like. A delivery confirmation is absent concerning the data transmission of the unidirectional communication. Therefore, the same data or an error correction code generated from the same data is continuously transmitted, that is, consecutively transmitted, and soft decision combination is performed to perform error correction on a data receiving side.
In the cellular mobile communication system, a non-communication state with the mobile station is monitored and, when a fixed time or more has elapsed, connection is disconnected to avoid radio resources including context information and management information for the connected mobile state, which are managed in the base station, being unnecessarily continued to be secured and enable the radio resources to be allocated to other mobile stations. In the LTE standard specified by 3GPP (3rd Generation Partnership Project), it is not specified that the base station performs non-communication monitoring, which is monitoring of a non-communication state in a radio section. However, for example, Non-Patent Literature 1 discloses non-communication monitoring performed using “ue-InactiveTime” (see P306 to 307).